There are many causes of excessive daytime sleepiness but the most common treatable medical cause is Obstructive Sleep Apnoea Syndrome (OSAS), sometimes spelled Apnea. It probably affects at least 4% of middle-aged men and 2% of middle-aged women which makes it as common as moderate to severe asthma or insulin dependent diabetes.
Its importance lies in the need to treat its main consequences, which are noisy and disturbed nighttime sleep and potentially dangerous daytime sleepiness. It is now recognised that failure to treat daytime sleepiness can produce a greatly increased risk of road traffic accidents, a reduction in the ability to concentrate effectively at work, reduced alertness, a reduction in the sufferers quality of life and adverse effects on relationships between spouses and partners.
Sleep apnoea is a common disorder which occurs when the throat muscles relax during sleep leading to partial or complete blockage of the upper part of the airway in the area behind the tongue. This leads to the characteristic narrowing and vibration of the throat which produces snoring. In some people this relaxation is more marked, especially if the throat is naturally narrow to begin with, and the sufferer has repeated episodes when they have breathing pauses (apnoeic episodes) and fight subconsciously to keep their throat open whilst asleep. This results in very poor sleeping quality and thus the classical symptoms of unrefreshing nocturnal sleep followed by excessive daytime sleepiness are produced.It should be appreciated however that there are many causes of poor sleeping quality and excessive daytime sleepiness.
Potential Causes of Excessive Daytime Sleepiness in Adults
- Sleep deprivation
- Sleep apnoea
- Restless leg syndrome
- Drugs – alcohol, sedatives, stimulants.
Here is a very informative poster showing many of the problems caused by Sleep Apnoea.